Thread: STARS & Space
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Old 04-18-2011, 06:35 AM   #41 (permalink)
BadNick
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How about a little cosmological thought about where and why all this comes from?


Manyfold Universe
Superstring theory predicts the universe has ten or eleven dimensions. Why don't we see these extra dimensions? Perhaps we are living on a brane (short for membrane) - floating in a space of five, six or more dimensions, like a soap bubble in the bathroom. The "manyfold universe" theory asserts that the brane we live on could be folded over on itself many times, accordion-fashion (Figure 05). Light could travel only on the brane, but gravity could take a shortcut by jumping from one fold to the next. Nearby matter on other folds can be detected gravitationally as unseen dark matter, since its emitting light takes a long time to reach us traveling around the fold.



Pre-Big Bang Universes
The concept of branes floating in higher dimensional space has offered some new ideas about condition at the moment of Big Bang and further back to the time before the event (see Figure 08). According to general relativity, density and temperature become infinity at the moment of Big Bang. The nonzero size and novel symmetries of strings set upper bounds to physical quantities that increase without limit in conventional theories, and they set lower bounds to quantities that decrease. The string theory expects that the curvature of space-time increase as the history of the universe is re-winded backward in time. But instead of going all the way to infinity, it eventually hits a maximum and shrinks once more. The string theory also proposes some hazarded guesses about the pre-big bang universe. There are two popular models floating around - the Pre-Big Bang and the Ekpyrotic scenarios.
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